OKIDATA DOC-IT3000, Service Manual

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Service Guide DOC-IT3000/4000
Chapter 2 Principles of Operation
2.3.01 Doc-It Controller Block Diagram
The Doc-It Controller has five major functional blocks. They are as follows.
· 80960KB Processor
- The 80960KB operating at 16MHz or 20MHz is a 32 bit processor designed for
imbedded applications. The 512 byte on-chip cache, multiple 32 registers optimized
for register to register instructions and pipeline instruction execution
enable the 16MHz 80960 to run at sustained rates of 6 MIPS.
· Host Communications Controller
- The HCC is Okis proprietary ASIC which handles the communication between the PC
host and the 80960 processor. The PC can communicate with the Doc-It Controller in one
of three ways:
- 1) LPT port emulation. In this mode most applications can use the system printer directly
as the Doc-It Controller emulates all three of the PC LPT ports. With a
printer language such as PCL loaded in Doc-It Controller memory, an
operation to print a file is identical to that of printing a file loaded directly to a
PCL printer.
- 2) Oki I/O ports. These are the ports through which the PC controls the communications
between itself and the board. Interrupt status and control are passed via the I/O ports.
- 3) Page window in PC memory. In this mode the HCC acts as a memory page controller
for the PC host. Pages of memory on the Doc-It Controller are mapped to a
programmable 16 Kbyte window in the PCs memory. In order to increase performance
the HCC supports i960 Burst mode accesses. In the Burst mode, the HCC
accesses 16 bytes (4x32 bits) of data per Doc-It Controller local bus
request.
· Integrated Peripheral Controller
- The Integrated Peripheral Controller (IPC) ASIC consists of an 80960 interface module,
a page interleaved memory controller, a DMA controller, timer and interrupt
controllers and a Doc-It Engine and DAA (FAX) interface controller. The
memory controller is designed to interface with 1 Mbit or 4 Mbit DRAMs in
interleaved, fast page access mode. Physical banks can be logically
mapped to any place in the address space to optimize speed or skip over a
failed part without leaving a hole in the memory space. The controller
arbitrates memory requests from three sources (in this priority) 80960 requests, DMA (on
board) requests, and refresh requests. The Doc-It Engine interface consists of three
sections; the Printer controller, the Scanner controller and the Doc-It command interface.
· Doc-It Controller Memory Subsystem
- The Doc-It Controllers memory subsystem consists of three banks of DRAMs (256x4) in
ZIP packages and two available SIMM memory expansion connectors. The base
memory for the Doc-It 3000 is 5 MB, meaning that base memory of banks 0, 1 and 2 are
installed, with the memory expansion slots empty.
- The base memory for the Doc-It 4000 controller card is 7 MB, the base memory of
banks 0, 1 and 2 plus 1 MB SIMM installed in location U52 or U53. Additional 2